SELF-TESTING AND SELF-CALIBRATING DETECTOR
First Claim
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1. A sensor system comprising:
- a chemical detector associated with a measurement circuit that produces a measurement of the partial pressure of a gas from the output of the chemical detector, wherein said chemical detector comprises a electrochemical cell;
a reference gas releasing material comprising a metal hydride, wherein said reference gas releasing material releases a reference gas such that the partial pressure of the reference gas Is a function of the temperature of the reference gas releasing material, wherein a heater is positioned to heat the reference gas releasing material;
a temperature sensor positioned to measure the temperature of the reference gas releasing material and a control circuit that when activated delivers a known partial pressure of the reference gas to the chemical detector by controlling the heat generated by the heater and thereby the temperature of the reference gas releasing material; and
a calibration circuit that, during calibration, activates the control circuit, reads a measurement called a calibration measurement from the measurement circuit, and produces a calibration factor by comparing the calibration measurement to an expected measurement, while the calibration circuit also, during regular operation, produces a calibrated measurement from the measurement and the calibration factor.
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Abstract
A self-testing and self-calibrating detector utilizing an internally produced reference gas. A detector that is sensitive to a target analyte as well as a reference gas can be utilized. A gas releasing material, such as a heated metal hydride, releases the reference gas. The partial pressure of the reference gas is known as a temperature dependent physical property of the gas releasing material. During calibration, the material can be heated to release reference gas and a calibration measurement of the gas'"'"' partial pressure can be made and compared to an expected value. The comparison can then be utilized to calibrate the detector.
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Citations
21 Claims
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1. A sensor system comprising:
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a chemical detector associated with a measurement circuit that produces a measurement of the partial pressure of a gas from the output of the chemical detector, wherein said chemical detector comprises a electrochemical cell;
a reference gas releasing material comprising a metal hydride, wherein said reference gas releasing material releases a reference gas such that the partial pressure of the reference gas Is a function of the temperature of the reference gas releasing material, wherein a heater is positioned to heat the reference gas releasing material;
a temperature sensor positioned to measure the temperature of the reference gas releasing material and a control circuit that when activated delivers a known partial pressure of the reference gas to the chemical detector by controlling the heat generated by the heater and thereby the temperature of the reference gas releasing material; and
a calibration circuit that, during calibration, activates the control circuit, reads a measurement called a calibration measurement from the measurement circuit, and produces a calibration factor by comparing the calibration measurement to an expected measurement, while the calibration circuit also, during regular operation, produces a calibrated measurement from the measurement and the calibration factor. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. (canceled)
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9. A sensor system comprising:
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a chemical detector comprising an electrochemical cell;
a measurement circuit that produces a measurement of the partial pressure of a gas from the output of the chemical detector;
a reference gas releasing material comprising a metal hydride, wherein said reference gas releasing material releases a reference gas such that the partial pressure of the reference gas is a function of the reference gas releasing material'"'"'s temperature;
a heater positioned to heat the reference gas releasing material;
a control circuit that when activated delivers a partial pressure of the reference gas to the chemical detector by turning on the heater and thereby the temperature of the reference gas releasing material; and
a test circuit that, during testing, activates the control circuit, reads a measurement called a test measurement from the measurement circuit, and activates an alarm if the measurement surpasses an alarm threshold. - View Dependent Claims (10, 11, 12, 13)
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14. (canceled)
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15. (canceled)
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16. (canceled)
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17. A method of producing calibrated gas partial pressure measurements from a chemical detector comprising the steps of:
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intermittently generating a reference gas at a known partial pressure by heating a reference gas releasing material to a known temperature with a heater;
using a metal hydride as the gas releasing material;
exposing the chemical detector to the reference gas at a known partial pressure;
using an electrochemical cell as the chemical detector;
using the chemical detector to measure the partial pressure of the reference gas during those times that the reference gas is intentionally generated and thereby producing a measurement called a calibration measurement;
producing a calibration factor by comparing the calibration measurement and an expected measurement;
producing a calibrated gas partial pressure measurement by applying the calibration factor to a measurement obtained from the chemical detector during those times that the reference gas is not intentionally generated; and
containing the chemical detector, heater, and reference gas releasing material within a unit housing. - View Dependent Claims (18, 19, 20)
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21. (canceled)
Specification